Circuit interrupter



- March 9, 1943. upw s ETAL 2,313,159

CIRCUIT INTERRUPTER Filed Jan. 9, 1941 r 2 Sheets-Sheet 1 INVENTORS [eon l5. Ludw/g &

a Z354 {M Ban o/7207A Baker Patented Mar. 9 1943 2,318,159 CIRCUIT INTEBBUPTER Mn B. n Turtle Creek. Pa,

house Electric & Mannf and Beniaml P. assignon to Westingacturing Company, East Pittsburgh, Pa a corporation of Pennsyl- Application January 9, 1941, No. 373,856 19 Claiml- (Cl- 200-448) This invention relates to improvements in circuit interrupters extinguishers for blast type.

In the operation of circuit interrupters of the fluid blast type, it is of prime importance to direct the flow of fluid with respect to the arc in such a manner that rapid deionization of the arc stream and consequent are extinction takes place with a minimum expenditure of energy. It is also desirable to effect are extinction without causing the are energy to rise to a high value.

The instant invention contemplates a contact structure for circuit breakers of the fluid blast type which separates quickly to establish an arc of relatively short length and a fluid blast directing means so arranged with respect to the contact structure that at least one section of are adjacent one terminal end of the arc is subjected to a radial blast of fluid of high velocity. For this purpose, an insulating barrier plate is disposed a relatively short distance from the end of one contact terminal and has an opening therethrough in which the arc plays and which also serves as a discharge oriflce for the blast of fluid.

circuit 'interrupters of the fluid and more particularly to are Our invention also contemplates theme of a plurality of barrier plates having fluid discharge orifices therein, which barrier plates are arranged along the arc path for extending the interruptin ability of the breaker to high voltage circuits.

A further feature of the invention is directed to the provision of metallic inserts in the barrier plates of insulating material and defining the orifice contour. This arrangement has the advantage over barrier plates constructed mtirely of insulating material-in that itpreventserosion of the orifice surfaces by arc thereon. The metal oriflce insulating barrier plate is superior to an all metal barrier plate in that flashover between the barrier plates through the partially ionized exhaust gases is prevented.

repeated action of the Even when all metal barrier plates are mainrespect to the are to tained at a floating potential with contact terminals, the tendency for the strike between the plates is still present.

This invention also contemplates improving the interrupting ability of fluid blast circuit interrupters of the foregoing type by the provision of a fluid discharge passage through the arcing terminals so as to prevent the feeding of hot metallic vapor from the contactterminals into the regions of the arc stream where a rapid recovery of dielectric is essential for efllcient arc extinction.

A further improvement in the operation of the interrupter is provided by controlling the rate of discharge of the fluid through the arcing contact terminals with respect to the rate of discharge through the materially reduce any dead space caused by the streaming fluid in and about the arc stream at a point where a high dielectric condition should appear. The presence of a dead space in the arc path has a disadvantage in thatit cools slowly and abounds in hot ionized gas particles which feed into the arc stream thereby extinction more difllcult.

A still further feature of the invention resides in an arrangement of oriflce structure in a fluid blast interrupter for maintaining the arc in alignment with the fluid discharge orifices so as to subject the are at the oriflce to the full effect of the fluid blast and thereby prevent the fluid from by-passing the arc in the event the latter is permitted to move Further improvements as well as objects and advantages will become apparent in the following description of an embodiment of our invention as shown in the accompanying'drawings, in which:

Figure 1 is a side elevational view showing the circuit interrupter of our invention:

Fig. 2 is an enlarged sectional view of the arc extinguishing structure of the circuit interrupter shown in-Fig, 1;

Fig. 3 is a fragmentary sectional view showing e a different form of barrier plate which may be embodied inzthe arc extinguishing structure; and

Figs. 4 through 6 are fluid flow diagrams illustrating the principles of operation of our circuit interrupting device.

Although-our invention is applicable in some of its aspects to circuit interrupters of the fluid blast type, generally, we have shown in the accompanying drawings for illustrative purposes an interrupter employing compressed gas such as air as an arc extinguishing medium. with specific reference to the drawings, the reference numeral l designates a suitable frame work or base structurewhich carries a plurality of tubular insulators 9 and II. Supported upon the upper ends of the insulators 9 and H is a metallic casing I3 housing an operating mechanism, genadjacent orifices so as to making arc to one side of the orifice.

. tact 29 movable through the contact 21 into and out of engagement with a stationary tubular contact 25. The lower end of the moving tubular contact 29 extends irio the casing I3 and is operatively connected to the operating mechanism l5 as shown. An electrical connection is made by means of a conductor 3| from the lower end of the moving contact 29 to an operating arm 33 01 a disconnect switch blade 35 operative exteriorly of the casing l3. The outer end of the disconnect switch blade 35 coacts with a contact assembly 31 which is supported by a suitable terminal cap 39 mounted on top of a hollow insulator 4|. The insulator 4| is supported upon the right hand end of the frame 1 and may serve to enclose a current transformer or other metering equipment used in the control of the interrupter. The terminal cap 39 is also provided with a terminal 43 for connecting the interrupter to an external circuit. Thus, when the interrupter is in the closed circuit position, an electrical circuit is made from the line terminal 23, stationary contact member 25, movable contact member 29, flexible conductor 3|. switch actuating arm 33, disconnect switch blade 35, contact 31, terminal cap 39, to the other line terminal 43.

Operation of the moving contact 29 to the open and closed circuit positions as heretofore mentioned is accomplished by a suitable operating pressed air which, upon actuation of the contacts, is caused to flow from the storage tank 41 througha control valve 49 through the tubular support insulator '9 to the casing I3. The blast of compressed air is directed from the insulator 9 throughthe casing II by a tubular conductor 5| which joins the lower end of the insulator I1. The annular space 53 disposed about the tubular contact 21 within the insulator |1 serves as a compressed air conducting path to the are extinguisher |9.f The specific method of directing a blast of compressed air into the arc stream will become apparent from a consideration of a more specific description of the arc extinguisher structure.

The arc extinguisher l9 comprises a pair of metallic flanged'end members 55 and 51 joined by a plurality of bolts 59. The lower flanged end member is secured tothe upper end of the insulator l1 and is provided with an opening I through which the contact member 21 extends mechanism, generally designated at |5 which may be of a conventional form including a compressed air cylinder 45 which is operated by compressed air stored in a tank 41 supported on the base 1. Inasmuch as the specific form of operating mechanism is not material to the-specific invention involved, it is not deemed necessary to further illustrate or describe the same. It may be pointed out, however, that the operating mechanism I5 is of a type such that when the moving contact 29 has been moved to the full open circuit position, as shown in Fig. 2, the mechanism is effective to actuate the switch arm 33 so as to operate the disconnect switch blade 35 out of engagement with the contact 31 and move the blade 35 upwardly a distance suflicient to provide an air gap capable of withstanding high voltage. The disconnect switch feature in series with the arcing contacts of the circuit interrupter is now generally well known in the art and permits the use of a particular arcing contact spacing which is highly advantageous for bringing about efllcient arc extinction but which alone would not be suflicient to withstand high circuit voltages, following the cession of fluid flow. While various types of operating and switching mechanisms may be used with the arc extinguisher of this invention, one desirable type is that disclosed and claimed in Baker and Bakken Patent No. 2,282,153, issued May 5, 1942, to the assignee of this invention.

Upon withdrawal of the moving contact 29 from the stationary contact 25 to the position shown in Figure 2 when the interrupter is carrying load, an arc will be established between the stationary contacts 25 and 21. Extinction of thearc is accomplished by a blast of comand also through which gas may flow from the annular passage 53. The upper flanged end member 51 supports the insulator 2| and also has a central opening through which the upper stationary contact 25 may extend. Although an annular space surrounds the stationary contact 25 within the insulator 2|, this space is not used for directing the flow of compressed air since it is closed at the upper terminal end of the interrupter and serves merely to provide insulation between the contact member 25 and the insulator.

Disposedbetween the flanged end members 55 and 51. are a plurality of, in this instance 2. bafile members 6|, each of which has a central aperture or opening 63 therethrough. Each baffie member 6| has a metallic insert 65 of conducting material as copper, for example, disposed within the opening 63, which inserts are provided with an orificei'l disposed in alignment with the axis of the stationary contact members 25 and 21. Each barrier member BI is" also preferably recessed in the region of the insert 65 as shown so as to provide a length of orifice suitable for eflicient circuit interruption which has been determined as being less than the thickness of the barrier 6| required for mechanical strength.

It will be noted that the lower barrier member 6| cooperates with the lower end member 55 to,

provide a gas receiving chamber 69. Compressed air from this chamber flows as indicated by the arrows radially inwardly in the annular gap formed by the upper end of the contact 21 and the metallic insert 65 immediately above. In order to streamline this flow of gas, the upper end of the stationary contact 21 is provided with a hollow, pear-shaped insulating member II. The flow director 1| thereby coacts with the lower barrier 8| to direct compressed air into the are playing through the lower orifice 61 from the stationary contact 21.

In like manner, the upper baille 6| forms a similar compressed air receiving chamber 13 with the upper hollow end member 51. The chamber 13 is connected with the chamber 69 by a plurality of tubular members 15 which also serve to space the upper and lower barrier members 5| apart. Compressed air can thus flow from the lower chamber 69 through the tubular support 15 to the chamber 13 where it is directed radially inwardly toward the upper orifice 61 into the annular gap formed between the upper insert 55 and the lower end of the contact member 25. A flow directing member 11 similar to the member II is disposed about the lower end of the contact member 25 for the purpose of streamlining the fiow of compressed gas to the section of are playing between the stationary contact 25 and the upper orifice 81. This fiow of gas radially inwardly with high velocity at both the upper contact 25 and the lower contact 21 sub jects the arc sections playing within the orifices 61 to a strong deionizing influence as the stream of compressed gas is turned from its radially inward direction to a direction substantially parallel with the are as the discharge takes place through the orifice. Inasmuch as the discharge of compressed gas through each orifice G1 is directed toward the other, the direction of flow again changes as indicated by the arrows and now takes a direction radially outwardly in the space between the two barrier plate members 6|. A plurality of cooling members 19 disposed between the barrier plate members 6| adjacent their periphery serves to cool and more completely deionize the escaping arc gases. The cooling member 19 may be constructed of metal preferably of the form of heavy wire gauze or any other suitable form.

With further reference to Fig. 2, it will be noted that we have provided a third barrier plate 8| also preferably of insulated material disposed between the plates 6|. The plate 8| also has an aperture 83 centrally disposed therethrou'gh and in axial alignment with the orifices 61. The barrier or barriers 8| have comparatively little effect on the arc extinguishing opera tion other than to provide a means for maintaining the arc in alignment with respect to the orifices 61. It is desirable that the are be maintained in alignment and prevented from bowing laterally within the gas discharge'space between the barrier plates Bl so as to maintain a more uniform arc extirmuishing efiectof the gas blast upon the arc in the regions of each orifice 61. If substantial bowing of the are or movement thereof laterally were permitted, there would be a tendency for a large portion of the gas blast to blow past the are, as the blast discharges through the orifice, without exerting its maximum deionizing influence upon the arc. Thus, the barrier member 8i is instrumental in maintaining a more uniform. performance of the interrupter. 1

It should be noted that the barrier plates 6| are completely insulated from the contact members 25 and 21. Consequently, the metallic inserts 65 forming the orifices 61 are maintained at a floating potential with respect to the contact members 25 and 21. Inasmuch as the annular surfaces of the inserts 65 are relatively narrow in a radial direction, there is little tendency for the arc to form terminals upon the insert 65 and move radially outwardly in the gas discharge space between the barrier members 6|. The blast of gas of high velocity blowing through the orifices 61 generally prevents the formation of destructive cathode hot spots upon the metallic insert 65 and thereby maintains the orifice dimension substantially constant.

Although we have shown metallic inserts 65 for defining the contour of the orifices 61, it is to be understood that the performance of the interrupter does not depend upon their specific use. For example. the barrier plate i may be constructed in entirety of a refractory material. as shown inFig. 3. In such case, the orifice 81 I tacts.

is defined by refractory material which will have (8 substantially no effect on the arc extinguishing abilityof the interrupter but is perhaps not as satisfactory as metal in that more erosion will take place as a result of the repeated action of the are playing through the orifice. The use of a refractory material in general for the entire barrier plate ii is not as satisfactory as the use of a fibrous material, for example, with the metal insert 65, since the refractory material has less mechanical strength than fibrous material. The use of fibrous material throughout the barrier plate has the disadvantage that at'the higher currents an are playing near the material causes gas to be produced in quantities suflicient to establish a back pressure which greatly interferes with the arc extinguishing.

blast of gas, and thereby makes arc extinction more difilcult.

With particular reference to Fig. 2, it will be noted that the blast of gas flowing symmetrically and radially towards the section of arc adjacent both the contacts 25 and 21 is also caused to discharge in part through the passages provided through these contacts. The advantage of discharging a part of the gas blast through the contacts and the remaining part through the orifices 61 will become apparent from a consideration of the flow diagrams shown in Figs. 4 through 6.

Fig. 4 represents in schematic form an interrupter embodying a solid contact 84 and a barrier plate 85 having an orifice 81 disposed in alignment with the axis of the contact 84 and spaced a short distance from the contact. The arrows illustrate the direction of flow of compressed gas entering the short gap between the contact 84 and the barrier plate 85. Inasmuch as the flow radially inwardly towards the axis of the contact 84 and the orifice 8'l'must change its direction so as to flow parallel with the axis through the orifices 81, a-considerable dead space will occur as designated by the shaded area at 89. If a contact, that is solid, as shown at 84 is used. this dead space will be filled largely with ions emitted from the contact as well as hot metallic particles resulting from a hot cathode spot on the contact. The dead space 89, therefore, feeds charged particles into the arc stream and prevents building up of dielectric in the space between the'contact 84 and the cooperating electrode, not shown, which is essential to bringing about efiicient arc extinction. The carrying of hot metallic particles and ions from the contact into the arc stream can be largely eliminated by venting a portion of the blast through the contact as shown in Fig. 5. As there-shown. the contact 84 is provided with a passage 9| which has substantially the same cross sectional area as the orifice 81 so that a symmetrical fiow of gas is produced as indicated by the arrows. The dead space 89, however, in this instance, is quite large and extends a substantial distance axially of the orifice and contact 84, as well as in a direction at right angles to this axis. This large dead space cools very slowly and feeds hot gas into the arc path at points where a rapid recovcry of dielectric is necessary to bring about ef fective arc extinction. The disadvantages of the double orifice arrangement, as illustrated in Fig. 5, have been overcome in the instant invention by restricting or throttling the discharge of the arc extinguishing blast through'the hollow con- This is more clearly illustrated in Fig. 6.

As shown in this figure, the tubular or hollow contact 84 has a transverse partition 93 thereacross which has an' opening 85 which is of materially smaller cross section than the cross section of the contact at the base of the arc or of the orifice 81. The effect of restricting the flow through the hollow or tubular contact Bl is to distort the gas blast flow as indicated by the arrows in Fig. 6. It will be noted that the dead space 89 has been materially reduced in size and also has been'shifted downwardly towards the interior of the tubular contact. This arrangement then permits dielectric to build up more rapidly through the orifice 81 and thereby greatly improves the arc extinguishing ability of the structure. It will be noted that the general arrangement schematically shown in Fig. 6 has been applied to the interrupter of our invention as shown in Fig. 2.

The arrows in Fig. 2 designate the flow of arc extinguishing gas as flowing radially inwardly towards the two gaps formed respectively between the contact 25 and the upper metal insert 65 and the gap formed between the contact 21 and the lower metal insert 65. The flow then changes its direction, a portion of which flows axially of the contacts through the orifices 81 whereas the remainder flows axially in the opposite direction respectively through the tubular contact 25 and the tubular contact 21. The flow through the tubular contact 25 is restricted by a partition 91 having an aperture 99 therethrough. The flow through the contact 21 is restricted by the moving contact 29 and is controlled by the aperture lill through the latter contact. The gas discharge flowing through the aperture 99 is permitted to vent exteriorly of the interrupter through a vent pipe I03 extending from the top of the insulator 2|, as shown in Fig. 1. The portion of the gas blast discharged through the tubular movable contact 2! discharges from the lower open end of this contact into the operating mechanism casing ii.

The foregoing structural arrangement employing a double orifice at each stationary contact 25 and 21 -is admirably adapted for a circuit interrupter of at least two and one-half million kva. interrupting capacity at 138,000 volts. For an interrupter of this rating, we have found that a movable contact rod 29 of 1 diameter requires an orifice diameter of 1 and an orifice spacing from the ends of the contacts 26 and 21 of approximately 94;". Excellent results were obtained when the gas discharge apertures 89 and llil were from to '7 in diameter.

It should be noted that the barrier plates ii and the central barrier ll form a structural unit which, as heretofore explained, is clamped between the flanged end members 55 and 51 by the bolts 59. In order to more securely support the barrier plate 6| against the clamping action of the bolts 59 aplurality of spacing members Hi5 are disposed between the barrier plates I and through the central plate ll. In the event that it is desired to remove the barrier plate assembly unit, it merely becomes necessary to loosen the clamping bolts 59 so as to raise the upper end member 51 and then remove a sufllcient number of bolts 59 from one side of the interrupter so as to permit the barrier plate assembly to be withdrawn. The removal of the barrier plate assemblythus permits ready inspection of the contacts 25 and 21 in the event that this becomes necessary. 7

Although we have shown and described a specific circuit interrupting structure, it is to be understood that the same is for the purpose oi illus- 'trationand that changes and modifications may be made by those skilled in the art without departing from th spirit and scope of the appended claims.

We claim as our invention:

1. In a circuit interrupter of the fluid-blast type, a stationary contact having a fluid discharge passage therethrough, a barrier member of insulating material disposed in fixed spaced relation from the end of said stationary contact, said barrier member having an orifice therethrough in alignment with said contact, means for establishing an are from said stationary contact through said orifice in said barrier member, and means for projecting a fluid blast radially inwardly towards said arc, said fluid blast discharging along the arc through both said discharge passage and said orifice, the cross sectional area of said fluiddischarge passage in said stationary contact being smaller than the cross sectional area of said orifice in said barrier member to produce an unsymmetrical flow of fluid through said discharge passage and said orifice with a greater quantity of fluid discharged through said orifice than said discharge passage.

2. In a circuit interrupter of the fluid-blast type, a contact having a fluid discharge passage therethrough, an insulated barrier member spaced from the end of said contact and having an orifice therethrough, means for establishing an are from said contact through said orifice, and means for causing a flow of fluid under pressure radially inwardly towards said are and through said'discharge passage and said orifice, the fluid carrying capacities of said discharge passage and said orifice being so proportioned that a greater quantity of fluid is discharged through said orifice than said discharge passage.

3. In a circuit interrupter of the fluid-blast type, a hollow stationary member of insulating material, a plate-like member of insulating material arranged in spaced relation with respect to the end of said hollow stationary member of insulating material, said plate-like member having an orifice therethrough in alignment with said hollow stationary member oi insulating material, a hollow movable contact operable within said hollow stationary member of insulating material, and movable through aid orifice to establish an arc therein, means for causing a blast of arc extinguishing fluid oi. high velocity to flow between said hollow stationary member o1 insulating material and said plate-like member radially towards said are and discharge through said orifice and through said hollow contact.

4. In a circuit interrupter oi the fluid-blast type, a pair of arcing contacts arranged in spaced relation, at least a pair of plate members of insulating material disposed between said arcing contacts, said plate members being spaced from each other and said arcing contacts and having apertures therethrough in alignment with said arcing contacts, a movable contact operative through said apertures to make and break the circuit between said contacts, means for operatin: said movable contact to establish an arc -which plays through said apertures, means for then outwardly through the pace between said plate members.

5. In a circuit interrupter oi the fluid-blast type, a pair of hollow contacts arranged in spaced relation each of which has a fluid discharge passage therethrough, at least a pair of plate members of insulating material arranged in spaced relation with respect to each other and said hollow contacts, said plate member having apertures therethrough in alignment with said contacts, means for establishing an are between said contacts which plays through said apertures, means for projecting a blast of arc extinguishing fluid towards the arcing surfaces of each hollow contact, and means surrounding each hollow contact which coacts with an adjacent plate member to guide said blast of fluid radially to ward a respective section of arc and cause a portion of each fluid blast to discharge through said hollow contacts, the remaining portions of said fluid blasts being discharged through said apertures and caused to flow outwardly between said pair of plate members.

6. In a circuit interrupter of the'fluid-blast type, a pair of arcing contacts arranged in spaced relation, at least a pairof plate members of insulating material disposed between said arcing contacts, said plate members being spaced from each other and said arcing contacts and having apertures therethrough in alignment with said arcing contacts, means for establishing an arc between said contacts which plays through said apertures, means for projecting a blast of arc extinguishing fluid radially toward each aperture in the space between each arcing contact and the. plate member nearest thereto, said blasts of fluid discharging through said apertures into the space between said plates of insulating material, and a barrier member disposed in spaced relation between said plate members of insulating material and surrounding the are for holding the arc in substantial alignment with respect to said aperture.

7. In a-circuit interrupter of the fluid-blast type, a pair of arcing contacts arranged in spaced relation, at least a pair of plate members of insulating material disposed between said arcing contacts, said plate members being spaced from each other and said arcing contacts and having apertures therethrough in alignment with said arcing contacts, means for establishing an are between said contacts which plays through said apertures, means for projecting a blast of are ex-- tinguishing fluid radially from all sides toward each aperture, said blasts of fluid discharging through said aperture into the space between said plates of insulating material, and cooling means disposed between said plate members of insulating material for cooling and deionizing the fluid discharged from the space between said plate members.

8. In a circuit interrupter, means defining a pair of substantially enclosed arcing chambers arranged in spaced relation with respect to each other, an arcing contact in each chamber, the two adjacent walls of said arcing chambers having discharge openings therethrough disposed in alignment with said arcing contacts, means for establishing an are between said arcing contacts which plays through each of said discharge openings, means for establishing a blast of arc extinguishing fluid in each of said arcing chambers, and means directing each blast radially towards a section of are playing between its respective arcing contact and discharge opening to cause a flow of arc extinguishing gas through said discharge openings to subject the arc portion playing therein to a strong deionizing influence.

9. In a circuit interrupter, meansdefining a pair of substantially enclosed arcing chambers arranged in spaced relation with respect to each other, an arcing contact in each chamber having a discharge opening therethrough, an additional discharge opening in each of the two adjacent walls of said arcing chambers arranged in alignment with said arcing contacts, means for establishing an are between said arcing-contacts which plays through said discharge openings in said adjacent walls, means for establishing a blast of arc extinguishing fluid in each of said arcing chambers, and means directing each blast radially towards a section of are playing between its respective discharge openings to cause a blast of arc extinguishing fluid to flow through said openings, said discharge openings through said arcing contacts having less fluid carrying capacity than said discharge openings through said adjacent chamber walls to establish a flow of fluid in said latter discharge openings that builds up dielectric in the arc stream at a rate faster than it equal flow conditions were maintained through all discharge openings.

10. In a circuit interrupter, a pair of spaced hollow end members, an arcing contact insulatingly supported with respect to each end member, an arc extinguishing assembly disposed between said end members and said arcing contacts, said arc'extinguishing assembly including at least two spaced plates of insulating material each of which has a fluid discharge orifice therethrough and arranged in alignment with said arcing contacts and through which an are established between said arcing contact plays, means clamping said end members into engagement with said assembly to provide substantially enclosed arcing chambers about each arcing contact, means for producing a blast of fluid in each arcing chamber, and blast directing means for causing a radial flow of fluid toward the arc adjacent each arcing contact and through said discharge orifice, said clamping means for said end members when released enabling said are extinguishing assembly to be removed as a unit without disturbing the arcing contacts.

11. In a circuit interrupter of the fluid-blast type, a contact having a fluid discharge opening therethrough, a barrier member insulated and spaced from the end of saidcontact and having a fluid discharge opening therethrough, means for establishing an are from said contact through said, opening in said barrier member, and means for producing a flow of fluid inwardly towards said are between said contact and barrier member and out through said discharge openings, the fluid carrying capacities of said discharge openings being so proportioned that a greater quantity of fluid is discharged through one opening than barrier to new toward the arc and out through said orifice in the barrier.

13. Ina gas-blast circuit interrupter, an arc terminal member on which one end or an arc is established, said are terminal member having a gas exhaust passage therethrough, an insulated barrier having an orifice through which the arc plays positioned close to said are terminal member when the arc is being extinguished, said insulated barrier forming a partition between a gas receiving chamber and a gas discharge space from which gas may exhaust to the atmosphere, and means for introducing a blast of gas into the gas receiving chamber between said are terminal member and said barrier to fiow toward the arc and out through said gas exhaust passage in the arc terminal member and out through said orifice in the barrier into the gas discharge space and from there to the atmosphere.

14. In a gas-blast circuit interrupter, an arc terminal member on which one end of the arc plays, means of insulating material surrounding said are terminal member, an insulated barrier having an orifice through which the arc plays positioned from said means of insulating material surrounding the arc terminal member a distance less than the width of said orifice, and means for introducing a blast of gas into the space between said means of insulating material and said barrier to flow toward the arc and out through said orifice in the barrier.

15. In a gas-blast circuit interrupter, an arc terminal member having a passage therethrough into which gas may flow and exhaust to atmosphere, said arc terminal member having one end on the arc thereon and its other end at a distance therefrom, an insulated barrier having an orifice through which the arc plays positioned from said arc terminal member having the gas exhaust passage a distance less than the width oi said orifice, and means for introducing a blast of gas into the space between said are terminal member and said barrier to fiow toward the arc and out through said passage in the arc terminal member and out through said orifice in the barrier.

16. In a gas-blast circuit interrupter, an arcing member a stationary member of insulating material having a passage therein, an insulated barrier member having an orifice therein, said barrier member being spaced from said stationary member of insulating material a fixed distance less than the width of said orifice, a hollow contact member movable in said passage and through said orifice to draw an are from said arcing member and through said orifice, and means supplying gas to flow into the are from all sides in a concentrated blast through the space between said stationary member of insulating material and said barrier member and to flow out through said orifice and out through said hollow contact.

17. In a gas-blast circuit interrupter, a pair of arc terminal members between which an arc plays during interruption of the circuit, a pair of spaced insulated barrier members positioned between said arc terminal members during interruption of the circuit, each of said barrier members having an orifice for the arc and being spaced from its adjacent arc terminal member by a distance which is small compared with the distance between the pair of barrier members, and means supplying a blast of gas under pressure to fiow inwardly toward the are from all sides in the small space between each arc terminal and its adjacent barrier member and to flow out through the orifices in the barrier members.

18. In a gas-blast circuit interrupter, a pair of arc terminal members between which an arc plays during interruption oi the circuit, a pair of spaced insulated barrier members positioned between said are terminal members during interruption of the circuit, each of said barrier members having an orifice for the arc and being spaced from the ad- I jacent arc terminal member by a distance which is small compared with the distance between the pair of barrier members, means supplying a blast of gas under pressure to iiow inwardly toward the arc from all sides in the small space between each arc terminal and its adjacent barrier member and to flow out through the orifices in the barrier members into the space between the pair of barrier members, and insulating plate means in the space between the pair or barrier members.

19. In a gas-blast circuit interrupter, a pair of arc terminal members between which an arc plays during interruption of the circuit, each of said are terminal members having a vent passage therethrough, a pair of spaced insulated barrier members positioned between said arc terminal members during interruption oi the circuit, each of said barrier members having an orifice for the arc and being spaced from the adjacent arc terminal member by a distance which is small compared with the distance between the pair 01' barrier members, and means supplying a bmt of gas under pressure to flow inwardly toward the arc from all sides in the small space between each arc terminal and its adjacent barrier member and to flow out through the orifices in the barrier members and out the vent passages in the arc terminal members. I LEON R. LUDWIG. BENJAMIN P. BAKER. 

